The present invention relates generally to intraluminal endovascular prostheses which are used for repairing defects in vessels and other lumens within the body of a patient. More particularly, the present invention relates to systems and methods for forming, in vivo, a robust junction between one element of a modular endovascular prosthesis which has been implanted in a patient, and another element.
Aneurysms are discrete dilations of the arterial wall. One of the most common, and among the most life threatening, is an aneurysm of the abdominal aorta between the renal and iliac arteries. If untreated, the aneurysm dilates progressively with an ever increasing risk of rupture and hemorrhagic death.
One method of treatment is provided by direct surgical intervention, in which the defective vessel may be bypassed or replaced using a prosthetic device such as a synthetic graft. The risks involved in direct surgical intervention of this magnitude are great, and include an extensive recovery period and a high morbidity rate.
In recent years a less invasive method of treatment has evolved through a series of inventions. The details vary, but, conventionally, a resilient tubular conduit fashioned from flexible material (herein referred to as a “graft”) is introduced into the defective vessel by means of catheters introduced into the femoral artery. The graft may be attached to the non-dilated arteries above and below the aneurysm using expanding metallic or plastic cylinders which may include barbs or hooks. The fluid pressure on the diseased arterial wall is reduced by the barrier provided by the graft. The field of art has developed since its early stages and in certain circumstances the implantation of grafts in the patient in “modular” form is now possible and may be desirable. A modular graft is one made up of different modular elements, each of which is implanted in the patient at a different stage, the different elements then being joined to each other by a suitable junction in vivo—that is, after introduction into the patient's vascular system.
While modular grafts have the advantage of reducing problems such as twisting of the graft during deployment, their use and the necessary formation in vivo of a junction between their elements is nevertheless attended by numerous complications. The most troubling long-term complication specific to the junction includes disruption of the junction, which may be caused by dislocation of one element relative to another through vascular movement or may be the long-term consequence of downstream fluid force. Once a junction between modular elements of an endovascular prosthesis has been disrupted, fluid leakage into the region between the prosthesis and vascular wall will likely follow, thereby diminishing the efficacy of the prosthesis in reducing fluid pressure on the diseased vascular wall.
In the prior art, there are various kinds of junction formed in vivo between tubular elements of a modular prosthesis. Conventionally, the junctions used in the art may depend upon friction between the overlapping elements to hold the elements in place relative to each other. In other cases, the overlapping portion of one element may be adapted to form a frustoconical shape compatible with the overlapping portion of the other element. This serves to enhance the frictional connection between the elements and provides a degree of mechanical connection. However, each of these junctions may be disrupted by a relatively small force.
In the prior art of endovascular repair with a modular prosthesis, there therefore exists a need to form in vivo a robust and secure junction between modular elements which will not be dislocated by vascular movement or downstream fluid flow. The present invention addresses needs which are found in the prior art.